Glendale Muni Airport
Aircraft Accident/Incident Report

Glendale, Arizona 85307
Friday, May 22, 1992 11:30 MST

NTSB Narrative Summary Released at Completion of Accident

THE FLIGHT DEPARTED THE AIRPORT ON A LOCAL INSTRUCTIONAL FLIGHT. WHEN THE FLIGHT RETURNED TO THE AIRPORT THE CFI INSTRUCTED THE NONCERTIFICATED STUDENT PILOT TO EXECUTE A SIMULATED ENGINE OUT AUTOROTATION. THE STUDENT PILOT ENTERED THE AUTOROTATION AT A LOW MAIN ROTOR RPM, BUT DURING THE DESCENT THE RPM INCREASED TO THE LOW SIDE OF ITS NORMAL OPERATING RANGE. THE CFI ATTEMPTED TO TERMINATE THE AUTOROTATION AT 200 FEET AGL BECAUSE OF THE MARGINAL LOW ROTOR RPM, BUT WHEN HE APPLIED RAPID FULL THROTTLE THE ENGINE FALTERED AND THEN FAILED. THE CFI EXECUTED AN EMERGENCY AUTOROATIVE LANDING. ON TOUCHDOWN THE HELICOPTER BOUNCED, THE SKIDS DUG INTO THE SOFT DIRT ON THE SECOND TOUCHDOWN AND THE HELICOPTER CAME TO AN ABRUPT STOP AND ROLLED OVER. THE POST ACCIDENT ENGINE EXAMINATION DISCLOSED THAT THE ENGINE OPERATED NORMALLY THROUGHOUT ITS NORMAL OPERATIONAL PARAMETERS BUT WHEN THE THROTTLE WAS RAPIDLY APPLIED AFTER A PROLONGED IDLE THE ENGINE FALTERED. THE IDLE RPM WAS MARGINAL AND THE CARBURETOR HAD RECENTLY BEEN REPLACED.

NTSB Probable Cause Narrative

THE IMPROPER CARBURETOR IDLE ADJUSTMENT BY COMPANY MAINTENANCE PERSONNEL. CONTRIBUTING TO THIS ACCIDENT WAS THE CFI'S INABILITY TO ATTAIN ADEQUATE RPM AND THE SOFT DIRT.

Event Information

Type of Event Accident
Event Date 5/22/1992
Event Day of the Week Friday
Time of Event 1130
Event Time Zone Mountain Standard Time
Event City GLENDALE
Event State ARIZONA
Event Country --
Zipcode of the event site 85307
Event Date Year 1992
Event Date Month 5
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude
Event Location Longitude
Event Location Airport GLENDALE MUNI AIRPORT
Event Location Nearest Airport ID GEU
Indicates whether the acc/inc occurred off or on an airport On Airport
Distance from airport in statute miles 0
Degrees magnetic from airport 0
Airport Elevation 1066
Weather Briefing Completeness Unknown
Investigator's weather source Pilot
Time of the weather observation 0
Direction of event from weather observation facility (degrees) 0
Weather Observation Facility ID
Elevation of weather observation facility 0
Distance of event from weather observation facility (units?) 0
Time Zone of the weather observation
Lighting Conditions Day
Lowest Ceiling Height 0
Lowest Non-Ceiling Height 0
Sky/Lowest/Cloud Conditions Clear
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 35
Air Temperature at event time (in degrees celsius) 27
Dew Point at event time (in degress fahrenheit) --
Wind Direction (degrees magnetic) 0
Variable Wind Indicator Unknown
Wind Speed (knots) 0
Wind Velocity Indicator Calm
Wind Gust Indicator Unknown
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) --
Density Altitude (feet) --
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury None
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor --
Injury Total None 2
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 392
NTSB Notification Source --
NTSB Notification Date May 22 1992 12:00AM
NTSB Notification Time 1715
Fiche Number and/or location -used to find docket information 46126
Date of most recent change to record Dec 11 2000 2:55PM
User who most recently changed record dbo
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N7656T
NTSB Number LAX92LA214
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 91: General Aviation
Type of Flight Plan filed None
Flight plan Was Activated? --
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name COBB INTL
Aircraft Model EXEC 90
Aircraft Series Identifier EXEC 90
Aircraft Serial Number RI-5001
Certified Max Gross Weight 1425
Aircraft Category Helicopter
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? Yes
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 2
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection Continuous Airworthiness
Date of Last Inspection Apr 24 1992 12:00AM
Airframe hours since last inspection 38
Airframe Hours 235
ELT Installed No
ELT Activated Unknown
ELT Aided Location of Event Site Unknown
ELT Type --
Aircraft Owner Name COBB INTERNATIONAL, INC.
Aircraft Owner Street Address 300 S. 25TH AVENUE
Aircraft Owner City PHOENIX
Aircraft Owner State AZ
Aircraft Owner Country
Aircraft Owner Zipcode 85009
Operator is an individual? --
Operator Name COBB INTERNATIONAL, INC.
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? Yes
Operator Street Address 300 S. 25TH AVENUE
Operator City PHOENIX
Operator State AZ
Operator Country
Operator Zip code 85009
Operator Code
Owner has at least one certificate None
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Unknown
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not --
Indicates Domestic or International Flight --
Operator carrying Pax/Cargo/Mail --
Type of Flying (Per_Bus / Primary) Instructional
Second Pilot on Board Yes
Departure Point Same as Event Yes
Departure Airport Code
Departure City
Departure State
Departure Country
Departure Time 1045
Departure Time Zone MST
Destination Same as Local Flt dest & departure same, accident can occur anywhere
Destination Airport Code
Destination City
Destination State
Destination Country
Specific Phase of Flight Landing
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Dec 9 2002 10:59AM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 19
Runway Length 5350
Runway Width 75
Sight Seeing flight No
Air Medical Flight No
Medical Flight --